http://friendfeed.com/orli/be2ed423/new-on-gmail-lab-authentication-icon-for

http://twitpic.com/8xmr6

Oops, sorry for the not un-shortened URL. I'm sooo used to Friendfeed :)

<<Display a key icon next to authenticated messages from certain senders that spammers attempt to fake. Currently works for mail from eBay and PayPal only>>

http://s3.amazonaws.com/twitpic/photos/large/15006066.jpg?AWSAccessKeyId=0ZRYP5X5F6FSMBCCSE82&Expires=1246452680&Signature=UgNPsEo5YPq%2FW%2BDvd5RgcJLv6TU%3D

I guess it's related to: http://googlesystem.blogspot.com/2009/02/gmail-tests-pgp-signature-verification.html

I bet it's not. More likely, it's related to:
http://gmailblog.blogspot.com/2008/07/fighting-phishing-with-ebay-and-paypal.html
(probably an even more advanced technology for authentication)

Thanks for the credit.
Wow, it's been a while since I've been here in the forum!

[Name updated to link with older posts – Tony]